1. Field of the Invention
The present invention relates to a polycrystalline silicon manufacturing apparatus and manufacturing method that deposits polycrystalline silicon on a surface of a heated silicon seed rod to manufacture a polycrystalline silicon rod.
Priority is claimed on Japanese Patent Application No. 2007-307444, filed Nov. 28, 2007, the content of which is incorporated herein by reference.
2. Description of Related Art
A manufacturing apparatus by Siemens method has been known as this kind of polycrystalline silicon manufacturing apparatus. This polycrystalline silicon manufacturing apparatus has a configuration for providing a large number of silicon seed rods in a reactor to heat the seeds, supplying raw gas consisting of mixed gas of chlorosilane gas and hydrogen gas to this reactor, and depositing polycrystalline silicon by contacting the raw gas with the heated silicon seed rods.
In such a polycrystalline silicon manufacturing apparatus, the silicon seed rods are fixed on electrodes provided on the inner bottom of the reactor in the standing state, and the upper ends of the seed rods are coupled by short-length connection members while forming a pair in order to form the π character shape. Moreover, a plurality of supply ports for the raw gas are provided on the inner bottom of the reactor, and is arranged to be dispersed among the large number of standing silicon seed rods. Then, in the polycrystalline silicon manufacturing apparatus, electricity is conducted from the electrodes to the silicon seed rods, the silicon seed rods are heated by resistance of the silicon seed rods and the raw gas ejected from the lower side is contacted with the surfaces of the silicon seed rods to deposit the polycrystalline silicon.
However, when the number of the silicon seed rods are densely increased, there is a problem that it becomes difficult to stably supply the raw gas to each surface of the silicon seed rods, the silicon seed rods swing and fall down due to a turbulent flow of the raw gas, and so on. The reason is that condition of upward flow, concentration, or the like of the raw gas becomes unstable particularly in the upper portions of the silicon seed rods due to the interference of the upward flow of the raw gas and the downward flow of exhaust gas because exhaust ports for exhaust gas after a reaction and the supply ports are generally provided on the inner bottom of the reactor.
Therefore, for example, Japanese Patent No. 2867306 discloses a nozzle for supplying raw gas that has a two-staged structure consisting of an upper nozzle for supplying raw gas toward the upper portions of the silicon seed rods and a lower nozzle for supplying raw gas toward the lower portions of the silicon seed rods and sufficiently supplies the raw gas to the upper portions of the silicon seed rods. Alternatively, Japanese Patent No. 3345929 discloses an apparatus that arranges the exhaust ports for exhaust gas in the upper portion of the reactor rather than the inner bottom of the reactor and exhausts the exhaust gas without interfering with the upward flow of the raw gas.
In this manner, although there has been performed the invention in which the gas flow in the reactor is preserved in an appropriate state to manufacture the polycrystalline silicon, it is desired that further high control for gas flow is demanded and high-quality polycrystalline silicon is produced more efficiently with increases in the size of the reactor and in the density of the silicon seed rods.